Memory ticking.

Running XP Home/SP3 with 3gb Corsair memory, the ones with the led lights on, on dual channel.

This morning after turning computer on and everything settled got a clicking sound, almost like a clock, clicks about every second, traced it to inside computer and on every click the lights on the sticks in slots 1and4 only, lit up like a christmas tree, I had just started up a 3D pool game which is quite memory intensive, turning the game off didn't stop the clicks neither did restarting the computer.